MIT Discovers New Material to Harness Energy, Generate Electricity With Water, Without Waste

By Kristopher SettleJanuary 15, 2013

The Massachusetts Institute of Technology (MIT) has never been complacent about sharing their fair share of gadgetry and breakthroughs in technology. From razors to wind tunnels, the microchip and prosthetics – MIT knows their way around innovation.

Announced this week, their newest discovery is a breakthrough material possessing the ability to harvest energy and generate electricity. If that wasn’t enough, the new polymer doesn’t require an electric charge or any other kind of external energy source to initiate. Rather, all it requires is trace amounts of water vapor.

The material consists of two separate polymers that are integrated into one another; polypyrrole, a sturdy but bendable material that maintains the compound’s structure, and polyol-borate, a soft gel that expands and contracts when water vapor is nearby.

The way the material works is as follows: First, when water is introduced, the polyol-borate forces the bottom layer to curl away from the exposed surface. Once the bottom layer is exposed to air again, the moisture is released, the material somersaults forward, and the cycle repeats itself again and again until the water is removed. Mechanical energy is produced by the repetition.

“What’s really impressive about this work is that they were able to figure out a scheme where a gradient in humidity would cause the polymer to cyclically roll up, flip over and roll in the other direction, and were able to harness that energy to do work,” says Ryan Hayward, associate professor of polymer science and engineering at the University of Massachusetts at Amherst.

MIT researchers believe the material can not only harvest energy from water vapor, but it can also generate electricity without any waste product like carbon dioxide. When coupling the polymer film with a device to convert mechanical energy to electricity (known as a piezoelectric material) it can generate an average charge of 5.6 nanowatts. Although this may not seem like much, it can be used on a small scale for many purposes like temperature and humidity sensors, or even monitoring sensors on clothing with evaporating sweat as the ‘water source’.

In addition, one of the more impressive features of this new creation is the amount of physical energy it exudes. Being referred to as ‘artificial muscle,’ a 25-milligram film is able to either lift up nearly 400 times its own weight or carry metals ten times its weight across a flat surface.

Mingming Ma, lead author for the paper being featured in Science on the material, sees value in harnessing its continuous motion and durability to drive robotic limbs in the future, “[w]ith a sensor powered by a battery, you have to replace it periodically. If you have this device, you can harvest energy from the environment so you don’t have to replace it very often.”

Looking similar to black, dancing cheese singles, you can check out the video for how the material interacts with water here. “We are very excited about this new material, and we expect as we achieve higher efficiency in converting mechanical energy into electricity, this material will find even broader applications,” says Robert Langer, professor and senior author of the paper being featured in this month’s Science.